Although particularly well-suited to warn and alarm a very high percentage of a population, siren networks are often reduced because of financial considerations. Instead, authorities tend to use already existing broadcast means like radio and TV for disaster information dissemination. To reach most of a population all over an area or state, there is need for an efficient and modern “wake-up” means to alert and request people to switch on a media receiver for further information.
There are solutions based on different technologies like Cell Broadcast in mobile networks or alarm clocks triggered by a centrally broadcast longwave time reference signal such as the DCF77 signal in Germany. In fact, conventional radio controlled clocks can be adapted by means of new software to receive alarm signals and to emit an optical and/or acoustic alert.
After all, fixed telephone networks are highly capable to fulfil this task because almost a hundred percent of all people in developed countries possess a connection to a fixed telephone network. While the above mentioned solutions may be restricted by a temporally limited availability or a limited spread of these technologies, a fixed telephone networks solution can easily provide an alarm to a geographically defined subscriber group such as the neighbourhood of a leaking chemical plant. Also in case of power down, a fixed telephone networks solution has a greater robustness than other solutions. Moreover, fixed line telephone extensions usually are not switched off and thus guarantee a 24 hour availability.
Existing solutions for broadcast calls over fixed telephone networks either have a long dissemination time or the network will run the risk of overload. Also, the flexibility to define every possible subscriber grouping is not given in these solutions.
It is the object of the present invention to provide an improved broadcast call system.
The object of the present invention is achieved by a method of controlling a broadcast call in a telecommunications network comprising switching units for providing telephone connections to subscribers of the telecommunications network, whereby the method comprises the steps of triggering, by one of one or more trigger servers of a broadcast call control system operating in parallel to the telecommunications network, a broadcast call by specifying data identifying a group of subscribers of the telecommunications network to be reached by the broadcast call and an announcement to be made to the group of subscribers in the broadcast call, requesting a connection setup to each subscriber of the group of subscribers in a cascade, and replaying the announcement to each subscriber a connection has been established to. Further, the object of the present invention is achieved by a broadcast call control system for controlling a broadcast call in a telecommunications network comprising switching units for providing telephone connections to subscribers of the telecommunications network, whereby the broadcast call control system is adapted to operate in parallel to the telecommunications network, and whereby the broadcast call control system comprises one or more trigger servers adapted to trigger a broadcast call by specifying data identifying a group of subscribers of the telecommunications network to be reached by the broadcast call and an announcement to be made to the group of subscribers in the broadcast call, request a connection setup to each subscriber of the group of subscribers in a cascade, and initiate the replaying of the announcement to each subscriber a connection has been established to.